Wine Country in SoMa: a vineyard on the Chronicle's rooftop

CLOS CHRONICLE We launch a tiny vineyard with help from a top Wine Country grower

Jon Bonné

Published
4:00 am PDT, Sunday, March 25, 2012

Napa viticulturist Annie Gavia plants a grapevine in the Chronicle rooftop garden on Monday, March 5, 2012 in San Francisco, Calif.

Napa viticulturist Annie Gavia plants a grapevine in the Chronicle rooftop garden on Monday, March 5, 2012 in San Francisco, Calif.

Photo: Russell Yip, The Chronicle

Photo: Russell Yip, The Chronicle

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Napa viticulturist Annie Gavia plants a grapevine in the Chronicle rooftop garden on Monday, March 5, 2012 in San Francisco, Calif.

Napa viticulturist Annie Gavia plants a grapevine in the Chronicle rooftop garden on Monday, March 5, 2012 in San Francisco, Calif.

Photo: Russell Yip, The Chronicle

Wine Country in SoMa: a vineyard on the Chronicle's rooftop

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Editor's note: In this occasional series, called Clos Chronicle, The Chronicle's wine editor, Jon Bonné, teams with winemakers for an urban viticulture experiment in our rooftop garden. Throughout the season, he'll report on his progress and offer tips for home gardeners interested in planting their own backyard vineyard. Today he reports on getting started.

For years, The Chronicle's Food & Wine building has had a garden atop its roof. On the food side, our modest produce - herbs, Meyer lemons, the occasional ground cherry - goes to our test kitchen, as does the honey from our industrious bees.

The wine side, however, has never joined in the fun. But since we've tried apiculture, constructed a potato tower, seeded mushrooms and cultivated citrus, why not try grapevines?

And so, Clos Chronicle.

A "clos" (pronounced cloh) is a walled vineyard. While we have no fancy stone masonry, we were planting vines inside walled metal tubs. Plus, the roof has a sizable ledge so, if anything, our vineyard was double-walled.

The moment she heard about our roof garden, Favia - who worked for Napa vineyard maven David Abreu on such properties as Harlan Estate - was keen to help add vines to the mix. As someone who brings her work home with her - she planted an acre of Sauvignon Blanc in her front yard - she found our project was not so far-fetched.

We also figured our own modest attempt at viticulture in extremis might help guide home gardeners who'd like a row or two of vines.

Obstacles emerge

Initially, we hoped to tap into San Francisco terroir, but that proved slightly harder than expected. Before settling on the rooftop locale, we had hoped to plant a site just across the alley from our building, but that was subsumed by a parking lot. Other vintners have faced similar obstacles, of course, but in our case the site was already a parking lot - if an undertrafficked one.

Honestly, though, much of the soil in SoMa isn't terribly interesting for grapes. The ground under our building is classified by the U.S. Geological Survey as "urban land," which is a nice way of saying, "Not much of anything."

But Favia was keen on planting grapes into San Francisco soil, so I asked master gardener Fred Bove, our permaculture adviser, for ideas. Bove noted that vines had once grown in the city's patches of Franciscan bedrock, an appealing idea - the Franciscan series composes most of the interesting coastal vineyard soils - but Bove also pointed out that such heavy soils would be tough to transport to a roof.

In the end, we settled for good organic potting soil with a bit of compost.

Now, what to plant? The city's few attempted vineyards have usually involved Pinot Noir and Chardonnay. If you follow the planting suggestions of the Winkler scale - UC Davis' long-used guide to climate regions for grapes - that would fit what would seem to be a clear Region I spot, the coldest on the scale. (See climate sidebar.)

Avoiding the obvious

But those two grapes seemed a bit obvious. As California's most widely planted white grape, Chardonnay has landed in some very inappropriate spots - and, goodness knows, we don't need another single vine of the stuff in the ground. Same with Pinot: Of all red grapes, this sensitive variety has arguably been subject to the most geographical high jinks.

We also ditched some typical choices in colder locales - hybrids or crosses like Seyval Blanc. They occasionally make interesting wine, but if nothing else California prides itself on growing vinifera, the classic European wine grape species.

What, then? I had been tasting a lot of wine from northern Italy. While the climates aren't the same, varieties there are grown in cold enough conditions that it seemed a decent analogue.

Several California winemakers have become interested in these grapes as well, and while Favia was adamant that we use official nursery cuttings - instead of borrowed vine material - there are now officially sanctioned versions of several such grapes.

I settled on two whites - Tocai Friulano and Malvasia Bianca, found widely in Friuli, and red Teroldego, native to the Trentino region.

Mostly, I was concerned about ripeness. Unlike some Friulian grapes, Friulano and Malvasia are moderate in acidity, so even if picked at low sugar levels, the resulting wine wouldn't be undrinkably screechy. (Malvasia has also long been used in California for its aromatic charms.) As for the red, Teroldego can become a solid rosé; if nothing else, we might end up with decent pink wine.

Securing grapevines on a small scale is tricky (see sidebar, plus sfg.ly/FPTNfF), but since we had help from professionals, I called Novavine in Santa Rosa, one of Northern California's biggest vine nurseries, to secure a few baby vines. Though the industry is facing a shortage of vine material, the nursery agreed to sell me a few of my esoteric choices.

Nearly all vines now planted in California are biological mashups. The vinifera that make wines we love have repeatedly shown themselves to be susceptible to the vine louse phylloxera, so most modern vines are in fact a graft of a specific clone of vinifera material to the rootstock of a native or hybridized vine.

Since we hoped to get a full season's growth, I needed dormant vines that had been grafted last year, grown and then stored. Like other nurseries, Novavine maintains a menu of clone and rootstock combos. If I was planting Merlot, I might have a range of options, but given the unusual choices, I could choose the sole clones of Friulano and Malvasia from UC Davis' Foundation Plant Services, and Teroldego from the Italian nursery Vivai Cooperativi Rauscedo, to which I had to pay a small royalty, 40 cents for each of my three vines. I headed to Santa Rosa, returning with a plastic bag of sapling vines, nestled in wood shavings.

Arranging the rows

Sun in San Francisco is a rare commodity, but our roof gets unimpeded exposure save for the gleaming 32-story azure Intercontinental Hotel across the street - a defining factor of our terroir, if you will. We decided to arrange our planters more or less in the middle of the roof, lengthwise north to south, a few degrees from the typical alignment Favia uses in most vineyards. This would provide even sun to both sides of the vine rows ("rows" in this case being two or three vines).

On planting day, Favia brought several buckets of high-grade organic compost - but warned that it could compose no more than 20 percent of the total soil, lest the vines be overwhelmed with nutrients. We had drilled drainage holes in the bottom of the galvanized tubs that would house Clos Chronicle, which we covered with shards of terra-cotta pots. Then we began to layer the potting soil and compost to within a couple inches of the tubs' edges.

Out came my vine baggie. Favia began to inspect the vines, grading them for root length and even spacing.

"I would reject this plant," she said, holding one Friulano sapling, "because it doesn't have roots that go around 360 degrees."

We'd purchased a few extras, so we chose our best five: two Malvasia, two Teroldego and a Friulano (in case we wanted a white blend). We dug holes in the soil, about 2 feet down, as Favia trimmed the roots. An actual trellis would come later, but we inserted metal pencil rods into the holes, dropped in the saplings and filled in with dirt.

Next: cover crop. We chose to dot the planting tubs with flowering alyssum, in part because it helps to keep the topsoil loose without growing deep roots that compete for water, and in part because it draws beneficial insects - an easy way of improving the vine's ecosystem.

Just moist enough

Speaking of water, the vines needed a stiff drink - enough to bring the soil to field capacity, so a handful would stick together but not feel like clay.

"Dig down to the bottom of the container and see if it's moist," she suggested - certainly a cheaper option than the pressure bombs and sensors used in the best modern vineyards. Score one for the galvanized tub.

There would be more decisions in the weeks to come, particularly how to combat mildew in foggy San Francisco. But for now, with a week of rain due, Clos Chronicle was off to a well-hydrated start. Thoughts of clones and root-grading subsided and I started to imagine how we might blend a SoMa Cuvee.

Perhaps we'd let the juice sit on its skins to build some extra texture. Perhaps we could dry the grapes just a bit to make a passito-style sweet wine.

Is S.F. warm enough to grow wine grapes?

For all the fretting about San Francisco's chill - duly noted, Sunset residents - I wasn't convinced it was too cold for grapes.

San Francisco is never hot, of course, but it's never truly cold. After spending a lot of time thinking about the narrow climate band in grape-growing areas like the Sta. Rita Hills ( sfg.ly/wK8tFN), I wondered how much heat accumulation our sunny corner of the city near Fifth and Mission streets might get.

Relative heat for growing wine grapes is measured by the Winkler scale, developed at UC Davis. It is based on the belief that wine grapes need at least 50 degrees Fahrenheit to mature. Each degree above 50 per day counts as one degree-day, and the cumulative number for the growing season from April 1 to Oct. 31 determines an area's climate region. Anything 2,500 degree-days or less is cold Region I (meant for sparkling wine, Pinot Noir and the like), while 2,501 to 3,000 is Region II (which can sustain Cabernet).

San Francisco climate data for such purposes is surprisingly hard to pin down. The closest weather station tracked by UC Davis was at SFO. I asked Pam Peirce, The Chronicle's Golden Gate Gardener columnist, who had rarely heard of wine grapes growing in the city but agreed to send some historical data.

Finally, I located average daily highs and lows for each day during the period under which the Winkler scale operates, and plugged them into Davis' model. I assumed we would land somewhere shy of 2,000 degree-days, likely placing us in the low end of Region I. (By comparison, Napa ranges from Region II to IV.)

To my surprise, the cumulative degree-days were 2,128 - not only adequate for grapes, according to the Winkler scale, but not far off from some cooler parts of the Sonoma coast or Santa Barbara.

I suspect that calculation in part underscores the shortfalls of the Winkler classifications - the model doesn't factor winter dormancy in our mild winters, for instance. But, if we needed enough heat to grow grapes, the data said we had it.

- Jon Bonné

Where to buy vines and supplies

While nurseries often must begin preparing vines a year in advance, there's still time to get vines in the ground this year - even though California is in the midst of a grapevine shortage because of a sudden boom in commercial planting.

Commercial nurseries like Novavine typically don't sell to home gardeners. The following are among the retail nurseries that will sell to home gardeners, but check to be sure vines are available.

9 steps to grapevines at home

1 Grading the vines: Old vine-grading standards called for at least 1/4-inch thickness for sapling vines, but Annie Favia suggests looking for perfectly round specimens with an even diameter and even root distribution all the way around the base.

2 Aligning the vines: If you're planting several vines in a row, you'll typically want them along a north-south axis to get even sunlight throughout the day. In Napa, Favia tends to plant rows pointing about 15 degrees east of north for more morning sun and leaf protection at the hottest time of day. It's less of an issue in cooler spots like San Francisco, where the goal is for the vine to get the most sun.

3 Soil: Determining what to grow in your soil is nearly as old an issue as wine itself. Your best bet is to chat with a nursery about various rootstocks and varieties. Generally you'll want well-drained soil with good organic matter, and if you're end-running terroir by planting in a container, as we are, most potting soils will offer excellent drainage and organic matter.

Compost is an important part of establishing soil health, but too much will "burn" the plants by overloading them with nutrients. Favia suggests a maximum of 20 percent.

4Trimming roots: You'll want to expose the vine roots before planting and trim them. Favia grabbed them in a fist, cut them to about 4 inches and inserted them into the holes straight down - all to help prevent J-rooting, where roots will start migrating back up toward the surface.

5 Root depth: Your depth will vary, but the vine's graft union (where the vinifera plant, or scion, is attached to the rootstock) should sit about a hand's width above the soil, enough to get warmth from the soil but far enough that the scion's tendrils can't root themselves.

Start by digging about 2 feet down. Favia pushed the vine down as far as possible, packed soil back in to fill the hole, then pulled the vine up until there was resistance, and repeated until each vine showed that hand's width above the soil. "You want to really pack it down so you get rid of the air down there," she says.

6 Frost protection: Not a concern in San Francisco, but if your area gets frost, you might want to cover the new vine until frost passes. Either mound dirt around it above the graft with the scion, or place a milk carton with the bottom cut out around it and fill it with dirt or sawdust.

7 The trellis: We'll devise a proper trellis system in future columns, but to keep the vines and roots straight, insert a pencil rod into the hole, within about an inch of the vine. Once the vine is planted, use either biodegradable ties or twine to fasten it - anything more rigid could create girdling, with the tie cutting into the vine. Recheck for girdling as the vine grows, and keep tying it higher on the stake until it's high enough for a trellis.

In a sunny spot like Napa, Favia would take more care to place the vine on the east side of the trellis, to keep fruit on the morning side. But, she said, "It doesn't matter in San Francisco."

8Cover crop: Vineyards have thrived under many tilling and weeding philosophies, but Favia is a fan of doing less topsoil work. We emulated a system she saw Phil Coturri use at Oakville Ranch: planting shallow-root plants like alyssum under the vine rows rather than turning up soil, although she also suggested aerating the soil with a cultivator if you're planting in a container. The alyssum attracts lacewings and other beneficial insects. "It's basically biocontrol," Favia says.

Other companion plants include slow-growing clover. If you plan to rototill, legumes like favas or Miranda peas will help to fix nitrogen in the soil and make the soil more porous and biologically active without competing in the vine root zone.

9Watering: At planting, the goal is to get the soil to field capacity - fully moist without excess. If you have a drip line at home, Favia suggests a very slow rate, about 1/2-gallon per hour, until the soil is fully moist.

Her alternate option: Use a 5-gallon bucket with a tiny hole drilled at the bottom, 1/8 -inch or so, to deliver 5 gallons over about 4 hours as an establishing drink. (See photo below.)

The vines would continue to need regular watering, although philosophies about vine stress vary enough that we figured we'd have to experiment a bit given our unusual setup.